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Co-infection Weakens Selection Against Epistatic Mutations in RNA Viruses

Froissart, Rémy and Wilke, Claus O. and Montville, Rebecca and Remold, Susanna K. and Chao, Lin and Turner, Paul E. (2004) Co-infection Weakens Selection Against Epistatic Mutations in RNA Viruses. Genetics, 168 (1). pp. 9-19. ISSN 0016-6731. doi:10.1534/genetics.104.030205.

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Co-infection may be beneficial in large populations of viruses because it permits sexual exchange between viruses that is useful in combating the mutational load. This advantage of sex should be especially substantial when mutations interact through negative epistasis. In contrast, co-infection may be detrimental because it allows virus complementation, where inferior genotypes profit from superior virus products available within the cell. The RNA bacteriophage φ6 features a genome divided into three segments. Co-infection by multiple φ6 genotypes produces hybrids containing reassorted mixtures of the parental segments. We imposed a mutational load on φ6 populations by mixing the wild-type virus with three single mutants, each harboring a deleterious mutation on a different one of the three virus segments. We then contrasted the speed at which these epistatic mutations were removed from virus populations in the presence and absence of co-infection. If sex is a stronger force, we predicted that the load should be purged faster in the presence of co-infection. In contrast, if complementation is more important we hypothesized that mutations would be eliminated faster in the absence of co-infection. We found that the load was purged faster in the absence of co-infection, which suggests that the disadvantages of complementation can outweigh the benefits of sex, even in the presence of negative epistasis. We discuss our results in light of virus disease management and the evolutionary advantage of haploidy in biological populations.

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Wilke, Claus O.0000-0002-7470-9261
Additional Information:© 2004 Genetics Society of America. Manuscript received April 9, 2004. Accepted for publication June 8, 2004. We thank S. Duffy, D. Kysela, J. Wertz, K. O'Keefe, M. Travisano, and D. Weinreich for helpful discussions, C. Doutrelant for statistical advice, and P. Nuelsen and WPKN radio for moral support. Two anonymous reviewers provided useful comments for improving the article. This work was supported by grants to P.T. from the National Science Foundation (NSF; DEB-01-29089 and DEB-02-01860). C.W. was supported by NSF grant DEB-99-81397 to Chris Adami, and S.R. was supported by the Yale Institute for Biospheric Studies.
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Yale UniversityUNSPECIFIED
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Official Citation:Co-infection Weakens Selection Against Epistatic Mutations in RNA Viruses Rémy Froissart, Claus O. Wilke, Rebecca Montville, Susanna K. Remold, Lin Chao and Paul E. Turner GENETICS September 1, 2004 vol. 168 no. 1 9-19;
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:75898
Deposited By: 1Science Import
Deposited On:14 Apr 2017 19:58
Last Modified:15 Nov 2021 16:55

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